Process of producing modified lard



Patented Jan. 13, 1953 PROCESS OF PRODUCING MODIFIED LABD Karl F. Mattil and Frank A. Norris, Chicago, Ill., assignors to Swift & Company, Chicago, Ill., a corporation of Illinois No Drawing. Application November 4, 1950, Serial No. 194,188

10 Claims.

The present invention relates to the treatment of lard, and more particularly to the production of lard and lard-containing products having im-- proved properties.

Lard, commercially the most important triglyceride material from an animal source, is fat obtained from the fatty tissue of hogs by a heat, solvent or enzyme treatment of the fatty tissue. The most common method of obtaining lard from the fatty tissue of hogs is the so-called wet or steam rendering treatment in which the fat is separated from the tissue by means of pressure with hot water or steam to give What is known as prime steam lard. Another common method of obtaining lard is by the dry rendering process in which fat is removed from the fatty tissue by means of heat alone. The latter method of obtaining lard includes the kettle rendering process in which the fat is melted in a hot water or a steam jacketed kettle. Other methods of obtaining lard, such as solvent and enzymatic treatment of fatty animal tissue, while not widely used on a commercial scale, are potentially important sources of lard.

After recovering the lard from the fatty tissue, the lard is generally treated to impart certain desired characteristics thereto. Thus, the lard may be settled, bleached, refined, washed, filtered. and deodorized to yield a substantially odorless and tasteless product.

Lard is often further treated to impart thereto the desired degree of plasticity, as when the lard is to be used in baked products. This desired plasticity may be obtained by a process whichineludes compounding therewith hardened lardor an hydrogenated vegetable fat, incorporating air therein and chilling. Of particular importance in the texturizing process is the chilling step. This chilling of the lard may be accomplished by means of chill rolls or an internal chilling machine. In the former method molten fat is picked up on the surface of the internally chilled rotating rolls and then subsequently scraped therefrom and further worked to give the lard a uniform plastic consistency. Chilling by means of an internal chilling machine is accomplished by passing molten fat through a series of vertical or horizontal units where'the fat is supercooled and allowed to solidify while being rapidly Worked. The lard product treated in the foregoing manner is generally employed as a shorten- Heretofore the plasticity of the final product has depended to a great extent on the nature of the foregoing chilling operation, and the final plasticity has been highly sensitive to the con- 2 ditions of the chilling step. For this reason th operating conditions in the chilling step have necessarily been very critical and required very careful control.

Another important characteristic of a shortening is its creaming ability. This creaming ability is a measure of the amount of air that can be incorporated into a batter during the mixing operation. The greater the amount of air absorbed and retained by the fat, the greater the leavening efiect of the shortening. Thus, for example, the volume of a cake may be increased by the use of shortening possessing superior creaming properties. The creaming ability of a shortening may .be determined by measuring the density of the batter or dough, Or by measuring the volume of a cake in which the shortening has been incorporated. A high specific gravity indicates a relatively dense mass with only a small amount of incorporated air, while a low specific gravity indicates a light, flufiy mass having a large amount of air incorporated therein. In general, the value of a shortening increases with its ability to absorb air.

Still another very important characteristic of a shortening is its appearance, particularly after being held at the elevated temperatures frequently encountered during distribution and sale of the product. solidified animal triglyceride material such as lard and lardcontaining products frequently have a dull, waxy, and Vaselinelike appearance which becomes progressively more pronounced the longer the product is held. The appearance of lard and lard-containing products is generally considered much inferior to the appearance of vegetable shortenings which have been held under comparable storage conditions, since vegetable shortenings possess a smooth, satiny luster which is retained even after prolonged storage.

While lard has unsurpassed shortening properties, the vegetable shortenings are generally considered to have superior creaming and emulsifying properties as well as improved appearance and storing properties. One of the principal causes for the inferiority of the appearance, storing properties, creaming ability, and emulsifying properties of the lard is the needlelike, crystal formation which the lard glyceride molecules assume upon solidifying and which continue to grow during storage. The long, needle-like crystals impart to lard and lardcontaining products the waxy, rubber-like texture or graininess which becomes much more pronounced and highly objectionable on standing at the relatively high temperatures generally encountered when distributing through normal commercial channels. Although it has been found possible to temporarily alter the crystallization pattern of lard by packaging while holding the lard at a carefully controlled, relatively low temperature; the lard'crystals soon revert to their natural long, needle like form when the lard is allowed to stand at room temperature. For this reason the foregoing temperature treatment during the packaging of lard is of no practical value when applied to lard which is to be distributed through normal commercial channels.

In order to overcome the-foregoing objectionable properties of lard and lard-containing products which have been found to be attributable to the normal crystallization habit of lard, it is an essential object of the present invention to permanently alter the normal crystallization habit of lard so as to preventthe formation of large, needle-like crystals during crystallization. and subsequent storage.

An additional object within the broadiscopeiof. the invention is to provide lard in which the heat of crystallization normally associated with the said lard is substantially altered.

Another object of the invention is'to provide a product containing lard having'improvedr lastic properties, including improved pliability and workability.

An additional object of the invention is toprovide a lard product having improved appearance characterized by a smooth velvety sheen.

A" further object of the invention is to provide a lard product having properties which equal or excell those of vegetable shortening'while maintaining the superior shortening characteristic of lard;

Still another object of the invention is to-provide a lard product having improved baking qualities, including enhanced emulsifying and creaming properties.

A still further object of the invention is to'provide a satisfactory lard product which may be texturized with a greater degree of flexibility in the operating conditions.

Still further objects of the'invention' will be apparent from the following description and claims.

In accordance with the present invention it is proposed to subject lard to a heat treatment in the presence of a substance capable of changing the crystallization properties 'thereof'under' conditions which do not cause an appreciable change in the melting point of the glyceride material or a significent change in the distribution of the several types of triglyceride molecules in" the fatty material being treated. The reaction which modifies the triglyceride molecules is highly complex and the mechanism is not completely understood. It has been observed, however, that the crystal habit and the heat of crystallization of the triglyceride molecules of lard are very significantly affected. And, since the substances capable of modifyingthe crystallization properties of triglyceride molecules do not become part of the crystal modified triglyceride molecules, the reaction appears to be catalytic. Therefore, the effective substances are herein referred to as crystal modifying catalysts.

Heretofore when a liquefied glyceride fatty material has been treated with certain catalytic agents, the conditions which have heretofore beenemployed cause a molecular redistribution terial which crystallizes from a solvent for the of the fatty acid groups between the triglyceride molecules and result in a change in the composition of the glyceride molecules. This redistribution has been termed interesterification or transesterification. The final result of the interesterification is a random distribution of the fatty acid molecules among the glyceride-molecules. The interesterification' is evidenced 'byan appreciable change in the melting point of the treated product and in the quantity of the triglyceride maglyceride product at a specific temperature. For example, when cottonseed oil is interesterified with any of the recognized interesterification catalysts'and under conditions employed heretofore, themelting, point and consistency of the glyceride material is significantly altered.

In marked contrast with the previous method ofcatalytically treating triglyceride material, the herein-disclosed crystal modifying treatment, does not cause an appreciablechange 'in'themeltingpoint of the material. a: change'in the chemical composition and structureof thefatty acid groups of the glyceride molecules, nor an apprecisable change. in the proportions of the several types of glyceride molecules in the material being treated. There appears to be no significant amount of interesterification of the glyceride molecules under the conditionsemployed inthe present invention as measured by the increase of trisaturated glycerides, although a small degree of interesterification has'beenobserved to occur during the crystal modification treatment and to continue after crystal modification has: been completed;

More, particularly the present invention-con templates: heating lard at relatively moderate temperatures: above the melting point ofthe highest melting point' components of said glyceride'material in the presence of a crystal modifying'catalyst foraiperiod' sufhcient to substantially alter the normal crystallization'habits of the" triglyceride molecules but without causing any significant amount of interesterification of triglyceride molecules;

Ithas' been found that a number of catalysts are effective in accomplishing the purposes of the present invention; Many'organic andinoraganic salts havebeen foundto be effective. Among the inorganic salts which have been successfullyem ployed to crystal modify lard are the halides, hydroxides, and sulfates-of tin; the halides, oxides, hydro-xide, and acetate'of zinc; the oxides; carbonate, acetate, and nitrate of lead; halides; hydroxides, acetate and'nitrate of cobalt; the halides, hydroxides, carbonates and sulfates of iron; and inorganic salts of antimony; cadmium, nickel, mercury, bismuth, aluminum, magnesium, and'titanium. Examples of inorganic'salts which have been successfully employed to crystal modify lard are stannous chloride, stannous hydroxide, stannous sulfate, stannic sulfate, and stannic chloride, zinc acetate, zinc chloride, zinc hydroxide, zinc oxide, zinc peroxide, zinc iodide, lead dioxide, lead carbonate, lead acetate, lead nitrate. red lead oxide, cobaltous chloride, cobaltous nitrate, cobaltous hydroxide, cobaltous acetate, ferrous carbonataferrous hydroxide, iron subsulfate, ferric chloride, antimony trichloride, cadmium oxide, nickel sulfate, mercuric bromide. aluminum chloride, aluminum stearate, bismuth nitrate, magnesium nitride, and. titanium tetrachloride. Other inorganic salts within the classes illustrated. and suggestedby the foregoing come po'sitions'may likewise be employed as catalysts in the present invention.

The effective amount of the foregoing polyvalent metal salts may range from about 0.01 per cent to about 3.0 per cent and higher and preferably between about 0.1 per cent and 2.0 per cent, based on the weight of the fat which it is desired to modify. The catalyst may be added in dry form, in the form of solution, suspension, or by means of a solid carrier, such as kieselguhr. The catalyst may also be added in the form of a saturated solution or slurry, or as a dilute solution, the amount to be added being calculated on the dry weight thereof. It is not desirable to add the crystal modifying catalyst in too dilute a form however, since large dilutions entail the removal of a greater amount of the solvent.

The most desirable concentration of any particular catalyst varies somewhat from catalyst to catalyst, depending largely on the activity of the particular catalyst chosen. In addition to variations clue to the activity of the particular catalyst, the optimum concentration of catalyst also depends somewhat upon the condition of the fatty material being treated. For example, when a catalyst such as stannous chloride or stannous hydroxide is employed, it has been observed that a lard having a high peroxide value requires a larger amount of catalyst to completely crystal modify than a lard which has a low peroxide value. It has also been observed that the peroxide value of a lard decreases appreciably when treated with a hydroxide catalyst such as stannous hydroxide. Thus, for example, when the lard to be modified has an initial peroxide value of 60, it has been found desirable to increase the concentration of stannous hydroxide to about 1.0 per cent, whereas the same lard having a peroxide value of around two or three requires only 0.2 per cent catalyst to crystal modify. Similar results have been observed when other catalysts are employed as the catalyst. It is therefore desirable to employ a lard having a relatively low peroxide value. It has likewise been found desirable to remove a large part of moisture initially present in the rendered lard before crystal modifying with the herein-disclosed catalysts.

The time of treatment required to crystal modify lard varies between about minutes and 6 hours, and preferably between about 1 hour and 5 hours. The optimum time of treatment required to produce crystal modified lard varies with the temperature, concentration of catalyst employed, and upon the condition of the triglyceride material being treated. Within the effective temperature range it can generally be said that at the lower temperature the speed of reaction is slower. When the concentration of catalyst is reduced below the optimum value, more time is required to complete the crystal modifying reaction. For example, treating lard with .07 per cent stannous hydroxide at a temperature of about 200 0. produces the same significant degree of crystal modification in 5 hours as 0.2 per cent stannous hydroxide employed at the same temperature produces in one hour. Likewise, it has been found that more time is required to complete crystal modification when the lard has been allowed to stand for prolonged periods after rendering and before commencing the crystal modifying treatment. It is therefore desirable to employ a good quality, freshly rendered lard.

The temperature at which crystal modification is effected with the herein-disclosed crystal modifying catalysts varies between about 120 C. and

, above specified temperature range when employing the herein-disclosed catalysts, since at substantially lower temperatures the rate of reaction is so slow as to make the process commercially impractical, and at substantially higher temperatures the lard is damaged so as to make its subsequent bleaching and refining too costly for commercial operation.

In order to facilitate the crystal modifying reaction and to reduce to a minimum the amount of catalyst required, it has generally been found advisable to conduct the reaction in a closed system under an inert atmosphere. By exclud ing air during the treatment, there is less danger of damage being done to the triglyceride material so that the subsequent handling thereof is facilitated and rendered less costly.

The lard may be heated in the presence of the catalyst at any stage of processing, and the beneficial results of the crystal modifying treatment are not impaired by subsequent processing such as deodorization and hydrogenation. It is also unnecessary to hold the crystal modified product at any particular temperature in order to retain the beneficial properties imparted to the material. It is preferred to treat the lard with the catalyst prior to refining thereof.

Where it is desired to omit the treatments generally employed to impart improved characteristics, the rendered lard may advantageously be directly heated in the presence of the hereindisclosed catalysts to produce crystal modified lard.

The following specific examples should be considered as merely illustrative of the herein-disclosed process and resulting product and should in no way be construed to limit the invention to the particular materials or conditions disclosed therein. In all cases the treated lard possessed a striking appearance, which was quite different from that of untreated lard. The treated lard had a characteristic satiny luster that readily distinguished it from conventional lard. In addition the plastic properties of the treated lard were superior, and cakes made therewith had a larger volume and a finer grain and texture than the cakes made with untreated lard, indicating that dough prepared with the modified lard is capable of entrapping greater quantities of air than is the case with dough made with untreated lard. The texture and fine grain of the cakes; also indicate a uniform dispersal of the air throughout the dough.

EXAMPLE I 2,000 grams of prime steam lard were admixed with one-half per cent zinc chloride based on the weight of the lard, and heated in an open flask at a temperature of 200 C. for a period of 3 hours with constant stirring. The treated lard was refined, bleached, and filtered.

The filtered lard was then chilled and rapidly agitated in an ice bath until plastic. A portion of the original untreated lard was also chilled in a similar fashion for comparison. The latter, product after chilling had a waxy, rubbery tex ture, while the chilled, treated lard was softer, more plastic, and resembled hydrogenated vegetable shortening in general appearance.

The two samples, cne treated and the other untreated, were tempered at 75 C. for a period TABLE 1.

Bloom Consistometer. Readings Temperature F.)

Untreated Lard Treated Lard 55cc M (nual:

In accordance with theprinciple'of theBloom consistency tester, the higher the numerical value obtained, the firmer the lard; Thus, at 75F. the catalytically treated lard was softer and therefore offered no resistance to the heat of the plunger of the consistometer. Consequently, a value of zero was obtained. The untreated lard at 75 F. was considerably firmer than the treated lard and, as a result, a reading of 34 registered on the scale.

The X-ray diffraction pattern of the treated lard more closely resembled that of hydrogenated vegetable shortening than that of the original prime steam lard. This further illustrates that there has been a fundamental alteration of the crystal structure of the lard as a result of the catalytic treatment in the specified manner.

In the baking tests with the treated and untreated lard samples, the'volume of a pound cake obtained with the treated lard was substantially greater than the volume of a cake made with the untreated lard. The specific gravity of the batter of the'treated lard was 0.750 as compared with 1.05 for the control sample of the untreated lard. The wet cream specific gravity of the treated lard was 0530 as compared with 0.750 of the control sample of the untreated lard.

EXAMPLE. II

2,000grams of" prime steam lard were admixed with 0.1 per cent zinc acetate based on the weight of. the lard, and heated in an open flask at a temperature. of 200 C. for, a. period, of, 4 hours with constant, stirring. The lard, was refined, bleached, and filtered. During th heating of the lard samples were taken at the intervals indicated in the following table:

TAB LE 2 Temperature C.)

It is: evident from the foregoing table that therehas been no significant change in thelard during the catalytic treatment. except that the:

free fatty acid content increased somewhat above: its initial value of 0.85 per cent. The slight drop in melting point is not considered significant since it'does not alter the subsequent process- TABLE 3 Pound Cake WetCream Sample Test, Sp. Volume Batter, Sp. Gravity (ca) Gravity i l, 280 1.05 0.800 1,340 0. 5 i 0.605 x 1, 345 0.795 1 0.610 4 1,385 0.810 1 0.010 5 f 1, 385 i 0.795 r 0.575

From the foregoing data it is evident that the volume of the pound cake increased with treatment for the first three hours, and the final wet cream and pound cake specific gravity were substantially below the original wet cream and pound cake specific gravity.

The treated samples possessed a much smoother. and more velvety appearance than did the control sample of untreated lard.

EXAMPLE III 2,000 grams of prime steam lard were admixedwith 0.2 per cent zinc acetate based on the weight of the lard, and heated in an open flask at a temperature of 200 C. for a period of 4 hours with constant stirring. The lard was refined, bleached. and filtered.

With the exception of an increase in the free fatty acid content, there is no significant change in the lard after treatment.

After chilling and agitating, there Was a very apparent difference in the appearance of the treated product as compared with the original untreated control. The original lard heated without a catalyst had a waxy appearance, whereas the final product after 4 hours of treatment had a velvety sheen and a smooth, creamy appearance. Also, when temperature readings of samples of the crystal modified lard and the unmodified lard were taken while being chilled and the readings plotted on temperature time coordinates, uniform cooling curves were obtained for the samples containin the crystal modified lard whereas there was a noticeable irregularity in. the cooling curves of the control samples of unmodified lard.

A portion of the final crystal modified lard was formulated into a shortening by compounding 86' percent treated lard with 14 per cent hydrogenating triglyceride material (50-60 titer lard) to give the desired consistency, and the compounded fat then chilled while being rapidly agitated. The foregoing sample and a control sample containing unmodified lard were then held at 75 C. for 4. days and tested by the bakery and gave the following results:

TABLE 4 Wet Cream Pound Cake Pound Cake sample Sp. Gr. Sp. Gr. Volume (cc) Treated 0. 590 0. 775 1,400 Untreated 0. 740 0.810 1, 280

Portions of the above samples were stored at a temperature of 97 F. and periodically compared with the control sample of the original lard which had been heated in the absence of a catalyst. While both the control and the crystal modified lard-containing sample exhibited a very satisfactory appearance at the end of the third day, there was a very noticeable difierence between the samples by the end of the second week. The control sample appeared to have a dull appearance and a stiff, relatively hard, crinkly texture,

whereas the crystal modified lard-containing sample retained its original sheen and smooth.

EXAMPLE IV 2,000 grams of killing lard were admixed with 2 per cent zinc oxide based on the weight of the lard, and heated in an open flask for a period of 2%; hours at a temperature of 225 C., with constant stirring. The treated lard was refined. bleached, and filtered.

The treated lard possessed the characteristic properties of crystal modified lard in that the specific gravity of the pound cake and the wet cream specific gravity were substantially below the specific gravity data of the untreated lard. Similarly, the pound cake volume obtained when employing the modified lard was substantially larger than that obtained with the untreated lard.

EXAMPLE V 2,000 grams of prime steam lard were admixed with 0.2 per cent zinc acetate based on the weight of the lard, and heated in an open flask at a temperature of 200 C. for a period of 2 hours with constant stirring. The treated lard was refined, bleached, and filtered.

After treatment, the lard had a substantially lower consistency than the original lard and, when incorporated into the standard pound cake batter without compounding with hard fat, produced a pound cake having a substantially increased volume compared with that produced by the original untreated lard used in the control pound cake.

In order to determine suitable catalysts and optimum operating conditions for the hereindisclosed crystal modifying treatment, it has been found necessary to employ one or more empirical tests. For example, it has been the practice to run a wet cream test, a water absorption test, and pound cake baking test on the crystal modifled lard or on the shortening comprising the crystal modified lard. By comparing the results of the foregoing tests on the treated lard with the results obtained on the control sample, it is possible to chart the course of the crystal moditying reaction and to determine when the crystal modifying treatment has taken place. Thus, when one observes a substantial decrease in the specific gravity of the lard-water emulsion in the wet cream test, 'a substantial increase in the amount of water which is taken up by the crystal modified material in the water absorption test, or an appreciable increase in the volume of a pound cake in the baking test, crystal modification will have taken place. Other tests based on the herein-disclosed characteristics of crystal modified lard may be conducted, such as taking Bloom consistency readings of the product being treated at temperatures above about 45 F., as the crystal modified product exhibits a substantially lower consistency between about 45 F. and the melting point of the product than does the unmodified lard at the same temperature.

While the foregoing wet cream test, water absorption test, and pound cake baking test are well known to those skilled in the art, the precise procedure employed in conducting these tests is as follows:

bowl and beater and then mix for five minutes at second speed. Weigh a representative 200 cc. portion of the creamed mass to obtain the specific gravity. Continue creaming at second speed, and take gravity readings again at 15 minutes and at 25 minutes. The bowl and beater should be scraped down after each gravity reading.

Total mixing time at second speed: 25 minutes Gravity readings to be reported: 5, 15, and 25 minute intervals Convert weighings into specific gravity and report as grams per cc.

Water absorption test Place one pound (454 grams) of shortening material at 75 F. into the 10 quart mixing bowl of the bench Hobart Model C-10 or equivalent mixer. Mix for one-half minute at second speed. Scrape down bowl and beater. Water at 75 F. is then added by means of a mayonnaise oil dripping tank at the rate of 30 cc. per minute, the machine running continuously at second speed.

The machine should be stopped at intervals and the water shut off in order to inspect the mix for unemulsified droplets of water. During these inspections, the upper rim of the mix should be scraped down. When droplets of water are present on the surface of the beaten shortening material, the machine should be turned on and run for two minutes with the water shut off. If the droplets are still present, the test is com.- pleted. If the droplets are absorbed, more water should be added until the above procedure shows unemulsified droplets present.

To maintain a constant flow of water (30 cc. per minute) a constant level should be kept in 1 1 the'salad oil tank. Report the grams of water emulsified by lpound of the shortening material.

Pound cake baking test (without monoglycerides) 1 Stir together well.

METHOD Have all ingredients at 75 F.

Weigh the ingredients of group 1 into the quart bowl of the bench Hobart Model C-lO mixer, mix at first speed for 30seconds and scrape down the bowl. (Note: This is apreliminary mixing period and is not included in the following mixing times.)

Cream 2 minutes at second speed and scrape down the bowl.

Cream 2 minutes at second speed, and again scrape down the bowl.

Cream at first speed for l'minute, adding onehalf of the ingredients of group 2 during the first 20 seconds. Add the ingredients of group 3 and cream 1 minute at first'speed.

Cream 1 minute at first speed, adding the other one-half of the ingredients of group 2 during the first 20 seconds.

Take specific gravity of the batter and scale 510 grams of the batter into a standard, paperlined loaf pan. Bake 65 to '70 minutes at 360 F. Allow cake to cool to room temperature before measuring.

Report volume-of finished cake and specific gravity of batter; also consistency and appearance of batter.

Pound cake baking test (with monoglycerides) FORMULA Lbs.

HOP NOMH Group 3: Whole eggs METHOD Have all ingredients at 75 F. Mix at first speed.

Scale the ingredients of group 1 into the 10 quart Hobart C-lO mixer bowl in the order. given. Scale the ingredients of group 2 separately and pour into the bowl with the ingredients of group 1, starting the machine immediately, very slow- 1y, so that the liquid and dry ingredients pick up without splashing. Mix for one-half minute and scrape down the bowl and heater. Mix for 3 minutes, not including the one-half minute interval at the beginning. Scrape down again and continue mixing for an additional 3-minute interval. Scrape down.

Add one-third of the eg s-(75 FJ andmixl 12 minute. Stop the machine and add one-third of the eggs. Mix another minute, then stop the machine. Add the final portion of the eggs,

scrape down well, and continue mixing for 2 .minutes to bring the total mixing time .to 10 minutes. Take the specific gravity.

Scale 510 grams of the batter into a regulation paper-lined loaf pound cake pan and bake at 360 F. for 70 minutes. The maximum allowable variation in baking time shouldnot exceed'5 minutes, depending on the load of the oven. Remove from the pan immediately after baking. Allow to cool to room temperature before measuring in the volume meter.

a. Report specific gravity reading at 10 minutes in grams per cc.

b. Report batter temperature.

0. Report the cake volume in cc.

d. In'addition, report such observations as consistency of the batter, appearance of the top crust and grain and texture of the cake.

From the foregoing specific examples describing the characteristics and improved properties of crystal modified lard it will be very apparent to those skilled in the art that crystal modified lard is particularly useful in the preparation of improved shortening products. Thus, any shortening product which hasheretofore consisted of .a substantial proportion of animal triglyceride material, such as lard, willbe, provided with verysubstantially improved baking and'storage properties as well as improved appearance, particularly after holding at moderate or elevated temperatures by substituting crystal modified lard for all or part of the unmodified lard in the shortening. The resulting shortening product has been found to have the desirable properties characteristic of an all vegetable shortening while retaining the superior shortening properties of lard. Further evidence of the fundamental alteration of the crystal structure of the lard toward that of a vegetable shortening is evident on observing that the X-ray difiraction pattern of the treated lard much more closely resembles the pattern of a hydrogenated vegetable shortening than that of the original lard. The foregoing hasbeen found to be true in all types of compounded animal fat and animal-vegetable shortenings where thesaid shortenings .containadded animal or vegetable hard fats and monoglycerides or are hydrogenated. Significantly, the improved results obtained with crystal modified lard are in no way dependent upon'the presence of monoglycerides since the desirable properties are enhanced by deodorization treatment.

It should thus be apparent that the improved lard obtained in accordance with the invention described herein can be used as an all-purpose shortening in place of both the animal and vegetable shortenings heretofore discriminately employed because of their peculiar properties. The improved lard may thus be advantageously em ployed in' the manufacture of cakes and icings as Well as in the preparation of bread and pie crust. Although we have illustrated the invention as being particularly applicable to'baked goods, it isalso applicable to 'oth'er'food'products, such as the manufacture of candy and fried products. It 'is also understood that the improved fat may be advantageously" used in lubricants, greases, cosmetics, medicated ointments, and in many other industrial applications.

This application is a continuation-impart application of US; patent application Serial No.

183,666, filedseptember 'l, i950, which is a con- 13 tinuation-in-part application of Serial 724,468, filed January 25, 1947.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. The process of treating lard to permanently alter the normal crystallization habit and improve the appearance and keeping qualities thereof, which comprises subjecting lard to a heat treatment at a temperature between about 120 C. and 260 C. for a period of between about one-half hour and 6 hours in the presence of a small amount of a zinc salt acting as a crystal modifying catalyst to permanently alter the crystal habit of the lard without causing a significant amount of interesterification, whereby the formation of long needle-like crystals is avoided.

2. The process substantially as described in claim 1 wherein the heat treatment is carried out at a temperature between about 175 C. and 225 C. for a period of between about 1 hour and 5 hours.

3. The process substantially as described in claim 2 wherein the zinc salt acting as the crystal modifying catalyst is zinc halide.

4. The process substantially as described in claim 2 wherein the zinc salt acting as the crystal modifying catalyst is zinc chloride.

5. The process substantially as described in claim 2 wherein the zinc salt acting as the crystal modifying catalyst is zinc acetate.

6. The process substantially as described in claim 2 wherein the zinc salt acting as the crystal modifying catalyst is zinc oxide.

7. The process substantially as described in claim 2 wherein the zinc salt acting as the crystal modifying catalyst is zinc hydroxide.

8. The process substantially as described in claim 2 wherein the zinc salt acting as the crystal modifying catalyst is zinc peroxide.

9. The process of treating lard to permanently alter the normal crystallization habit and improve the appearance and keeping qualities thereof, which comprises subjecting said lard to a heat treatment at a temperature between about 200 C. and 225 C. for a period of between about 2 and 5 hours in the presence of between about 0.1 and 2.0 per cent based on the weight of the lard of the crystal modifying catalyst zinc acetate to permanently alter the crystal habit of the lard without causing a significant amount of interesterification, whereby the formation of large needle-like crystals during solidification and subsequent storage is avoided.

10. The process substantially as described in claim 9 wherein the crystal modifying catalyst i zinc chloride.

FRANK A. NORRIS. KARL F. MATTIL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,309,949 Gooding Feb. 2, 1943 2,571,315 Vander Wal et a1. Dec. 10, 1949 FOREIGN PATENTS Number Country Date 249,916 Great Britain Mar. 30, 1926 

1. THE PROCESS OF TREATING LARD TO PERMANENTLY ALTER THE NORMAL CRYSTALLIZATION HABIT AND IMPROVE THE APPEARANCE AND KEEPING QUALITIES THEREOF, WHICH COMPRISES SUBJECTING THE LARD TO A HEAT TREATMENT AT A TEMPERATURE BETWEEN ABOUT 120* C. AND 260* C. FOR A PERIOD OF BETWEEN ABOUT ONE-HALF HOUR AND 6 HOURS IN THE PRESENCE OF A SMALL AMOUNT OF A ZINC SALT ACTING AS A CRYSTAL MODIFYING CATALYST TO PERMANENTLY ALTER THE CRYSTAL HABIT OF THE LARD WITHOUT CAUSING A SIGNIFICANT AMOUNT OF INTERESTERIFICATION, WHEREBY THE FORMATION OF LONG NEEDLE-LIKE CRYSTLS IS AVOIDED. 